1998 Volume 52 Issue 7 Pages 959-967
Anionic trash derived from mechanical pulp deteriorates the effect of retention aids and causes pitch problems in papermaking systems. The purpose of this study is to evaluate the pitch control ability of precipitated calcium carbonate (PCC). The adsorption of model pitch onto PCC with different particle sizes has been studied. Abietic and oleic acids and dissolved and colloidal anionic substances in mechanical pulp were used as model samples pitch in this study. Both abietic and oleic acids were adsorbed onto the PCC. However, the amount of adsorbed oleic acid on the PCC was much more than that of abietic acid. It was elucidated by the measurement of FT-IR that the oleic acid was adsorbed onto the PCC as a calcium oleate. The zeta-potential of PCC was changed from positive to negative with the adsorption of the model pitch. It was confirmed by infrared spectrum measurement that the model pitch adsorbed onto PCC formed calcium salts with calcium (II) ion on the PCC surface. The PCC particles were flocculated after adsorption of the model pitch, whereas the talc particles were not flocculated. This phenomenon can be explained by the difference in the adsorption mechanism.
Dissolved and colloidal substances in the TMP furnish were shown to be adsorbed on the PCC. By the measurement of the total organic carbon concentration (TOC) and colloid titration, it was shown that colloidal substances were adsorbed on PCC until anionic demand of the PCC was saturated. In addition, the colloidal substance of anionic trash tended to be more preferentially adsorbed on the PCC than the dissolved substance.
